1. Field of the Invention.
The present invention relates to the field of radio receiver mechanical tuner apparatus and more specifically to the area of mechanical tuner pushbutton assemblies.
2. Description of the Prior Art.
Several prior art patents, including U.S. Pat. No. 3,852,691, illustrate the typical arrangement in a manually actuated mechanical tuner pushbutton assembly as employed in a radio receiver. That assembly utilizes a plurality of depressible slides disposed across the front face of the radio receiver. The slide elements are disposed in a generally parallel arrangement and contain pushbutton end caps that extend outwardly from the ends of the slide elements for manual depression by the radio operator. Upon manual depression of the pushbutton end cap, the slide element is moved inwardly towards the tuner chassis until an associated locked cam mechanically reorients the internal tuning mechanism of the radio receiver to electrically select a particular reception frequency. Upon release of the pushbutton, an internal spring restores the slide element to its original position in which the cam remains locked. In order to reset a cam on the slide element to a new reception frequency, it is necessary to unlock the cam by pulling the pushbutton end cap away from the tuner chassis to a fully extended position. The tuning mechanism is then set, with a rotatable tuning knob, to a new reception frequency and the pushbutton is depressed until the unlocked cam is reset by the tuning mechanism to a new position and is then locked in that position by further inward movement of the slide element.
As such, conventional mechanical tuner pushbutton assemblies result in radio receivers that have pushbutton end caps with a relatively high profile extension from the front surface of the radio receiver in order to provide a gripping area for resetting.
In contrast, there is a tendency in the more expensive electronically synthesized tuning radio receiver design to provide a relatively flat front surface on the radio receiver with pushbutton switches that have a low profile extension from the front surface.